Process of refining ores



NITED STATES PATENT OFFICE.

ALBERT E. BARTON, OF ENSLEY, AND GEORGE E. MCOORMACK, OB PRATT MINES, ALABAMA.

PROCESS OF REFlNING ORES.

SPECIFICATION forming part of Letters Patent No. 519,901, dated May 15, 1894.

Application filed April 22, 1893. Serial No. 471,453. (No specimens.)

and GEORGE E. MCCORMACK, residing at Pratt Mines, Jefferson county, Alabama, have invented a new Process of Refining Ores, of which the following is a specification.

Our process is based upon the discovery of the fact that when hematite iron ores, orother similar ores, are subjected to the action of heat, in the presence of gases arising from the destructive distillation of coal, or in the presence of any other gases forming a reducing or neutral atmosphere with deposition of carbon, the phosphoric ingredients or elements in said ores are materially reduced, and to such extent that the resulting iron ore may be made into pig iron suitable for conversion into steel by the acid Bessemer, or by the acid open hearth process. It is well known that only those ores which are low in phosphorus are suitable for this purpose, and hence it is plain that a process, which produces from the phosphoric red hematite or similar ores, a pig iron suitable for steel making is of great value, particularly in those parts of the world where there is an abundance of such ores and where the ores in the natural state suitable for the purpose are not found, or if found, at least are not present in sufficient quantities for practical purposes. To reduce materially the amount of phosphorus in these phosphoric ores of hematite, or similar species, is the object of our invention; and more particularly to so reduce theamount of this impurity that the resulting ore may be made into pig iron capable of being readily converted into steel by one or the other of the processes above mentioned,that is by the Bessemer or by the open hearth process. Acting upon our knowledge of the well-known requirements of an ore for this purpose and upon the new fact which we have discovered, we have invented a process by which the desired result may be readily and economically obtained, as is hereinafter particularly described.

In practice, we have found that when the ores mentioned are submitted to the action of heat in a sufficient degree in the presence of gases, as above related, the amount of phos phorus in the ores is reduced from about twotenths of one per cent. and over to as low as about four-hundredths of one per cent.

In treating ores for steel making we prefer to use those ores in which a certain amount of carbonate of lime is intimately mixed; but when these ores cannot be obtained, or when the ores 6o to be treated do not contain this element, in its natural state, we effect the same result by the addition of a suflicient quantity of carbonate of lime, to perform the same function as that element does in an ore when it is found in the natural state. And when theore contains a less amount of this lime than is required, we, of course, add sufficientto make up the deficiency. Preferably the ore to be used should originally contain between .06 and .20 per cent. phosphorus.

In fossiliferous hematite ores the phosphorus is believed to exist as compound of lime andphosphorus, CaP O When hydro carbon gases, derived from the destructive distillation of coal, are passed over or through ore containing this phosphate of lime, free carbon is obtained from the hydro carbon and a reaction similar to that commonly obtained in the commercial extraction of phosphorus takes place, namely, SCaP,O +1OO=Ca P 0 (tri calcic phosphate) +1, +1000, that is two thirds of the phosphorus contained in the ore is liberated when it immediately combines with the hydro carbon present forming one of the volatile phosphorus bases or phosphines probably CH PH (methyl phosphine) which is volatile at ordinary temperature and so passes away to the stack with the other gases.

All hematite ores are to a certain extent impure and contain silica; now if silica is present in the above equation the following reaction occurs:

whereby all the phosphorus is freed. This reaction, however, only takes place at a very high temperature. With sucha temperature and with the reducing conditions necessary, 10c

a quantity of spongy iron would be found with which the freed phosphorus would be apt to combine; it lime be added a very high temperature is no longer necessary, an acid silicate of lime commencing to form at a comparatively low temperature, which absorbs the lime from the phosphate of lime forming a more basic silicate and leaving the Whole of the phosphorus free to combine with the volatile hydro carbon present as a phosphine, which is done under suitable conditions.

In carrying out our process upon a practical basis, we take either crushed ore or ore as it is mined and spread it, preferably in a thin layer, in a heating chamber or furnace connected by a pipe or flue with a coke oven or furnace used in the destructive distillation of coal. The heat derived from the gases may be reinforced by external heat applied to the heating chamber or furnace, when the latent heat of said gases is not sufficient to bring the ore to the requisite temperature. WVhere the distance between the reducing furnace and the gas producing apparatus is such that the gases suffer material reduction in temperature, such application will be necessary, though in all cases it may be used if found desirable. Any form of gas producing apparatus may be used for producing the gases which form a reducing or neutral atmosphere. Having placed the ore as stated, though more than one layer may be used if desired, and a vertical stack or furnace employed we then subject the ore to the action of heat in the presence of the gases allowing it to remain under this treatment at sufficient length of time to reduce the amount of phosphorus to the required degree, this time being dependent upon the nature and amount of the ore charged, ores of different phosphoric quality requiring different times. This matter can be easily regulated by any skilled metallurgist.

Any known form of reducing furnace may be used as the heating chamber, as the apparatus in which our process is carried out forms no part of our invention and requires no particular description herein.

The degree of heat required in the reducing chamber can be readily governed by any skilled metallurgist keepingin mind only that a sufficient degree must be maintained to effect the proper reduction in the amount of phosphorus for the object stated. For steel making, it must be sufficient to reduce the amount low enough to make an ore for pig iron suitable for conversion in the Bessemer or the open hearth process, already defined. We may state here that we have found that a temperature of about 1,500 Fahrenheit gives good results, but we wish it clearly understood that we do not limit ourselves in this 01' any other matter of detail, which may be varied to suit varying circumstances within the judgment of any one skilled in the art,

without departing from the spirit of our invention. 7

What we claim as our invention 1s 1. The herein described process of treat ng iron ores to free them from phosphorus wh ch consists in subjecting the ores to the ac tion of heat at a temperature of about 1,500 1n the presence of suitable reducing gases containing carbon, without reducing said ores substantially as specified.

2. The herein described process of dephosphorizing iron ores which consists in sub ecting them to the action of heat at a temperature of about 1,'500 in the presence of gases, arising from the destructive distillation of coal, without reducing said ores substantially as specified.

3. The herein described process of dephosphorizing iron ores which consists in sub ecting the same to the action of heat at a temperature of about 1,500 in a reducing chamber and at the same time passing gas es resulting from the destructive distillation of coal through said chamber, without reducing said ores substantially as specified.

4. The herein described process of dephosphorizing iron ores which consists in sub ecting a thin layer of ores in a reducing chamber, to the action of heat at a temperature of about 1,500 in the presence of gases resulting from the destructive distillation of coal, substantially as specified.

5. The herein described process of treat ng phosphoric ores which consists in spreading crushed or mined ore in a thin layer or layers in a heating chamber-and subjecting the same to heat at a temperature of about 1,500", in the presence of suitable reducing gases containing carbon whereby the amount of phosphorus therein is materially reduced, substantially as specified.

6. The herein described process of dephosphorizing iron ores which consists in mixing with the ores carbonate of lime, in suitable proportions, and then subjecting the mixture to the action of heat in the presence of reducing gases substantially as specified.

7. The herein described process of treating ores which consists in mixing with said ores carbonate of lime, in suitable proportion and subjecting the same to the action of heat while placed in a thin layer or layers, 1n a reducing chamber, and to the reducing action of gases resulting from the destructive distillation of coal, substantially as set forth.

In testimony whereof we have signed our names to this specification in the presence of two subscribingv witnesses.

,ALBERT E. BARTON.

GEORGE B. MCOORMACK.

Witnesses:

R. T. FRAZIER, CHARLES N. LARNER. 

